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Photography Tips - Depth of Field

 2nd Mar 2010

depth of field 18mm f3.5Depth of Field is one of the main creative tools in photography. ­ It’s where you get to control what’s sharp and what’s not in your photos.

But there’s more to controlling depth of field than just apertures.

By understanding and using depth of field you can get everything in your photos pin sharp, make messy backgrounds disappear and emphasise the subject.

I’m not going to give you a bunch of pretty pictures in this depth of field photography tip because I want to get you to understand and start working with the technique. You can then take that away with you and apply it wherever you like ­ and make your own pretty pictures.

depth of field 18mm f22The main control of your depth of field is with the camera’s
apertures. Those are the numbers beginning with ‘f’ in the LCD which go something like…

F3.5  f5.6  f8  f11  f16  f22  …….

Apertures can be controlled either manually ­ or by using the A (Aperture Priority) setting on the command dial. Canon and some other makes call it AV (Aperture Value) but it is exactly the same thing.

The higher the ‘f’ number you set ­ the greater the depth of field in your picture will be. Another way of saying it is ­ that more of your picture will be in sharp focus with high 'f' numbers. This is great for landscapes or macro close ups.

The lower the ‘f’ number you set the shallower the
depth of fdepth of field 250mm f5.6ield
will be. Use low 'f' numbers for shallow depth
of field when you want to have a sharp point in the picture but have a blurred background / foreground.

So …

  • f3.5 = shallow depth of field
  • f11 = middle depth of field
  • f22 = masses of depth of field


But there’s more - apertures aren’t the only thing controlling depth of field. The length of your lens makes a massive difference.

If you’ve been on a One-to-One photography course with me
depth of field 250mm f40chances are you’ve met my old mate Mr. Brick Wall before - if so this is a chance to re-cap!

Look closely at these ‘wall’ images.

Depth of field (the sharp part of the picture) stretches between the red lines - and the point of focus is the blue line.

The first two were taken using a short 18mm lens.

In the top pic I used a low ‘f’ number of f3.5 which makes the shallowest depth of field - and sharpness is only about a brick and a half long.

The second image was taken on the same 18mm lens focused on the same spot - but this time using f22. Now sharpness goes almost to the end of the drive!

The third and fourth pictures were taken on a 250mm lens.

shallow depth of fieldIn the third pic I used f5.6 which (despite being a higher ‘f’ number than in the first picture) has given a tiny depth of field. This is because of the longer lens!

In the fourth picture it’s the same point of focus again but I used an aperture of f40.

Even at this highest ‘f’ number the depth of field is only a few feet because longer lenses don't have as much depth of field as shorter ones.

Here are the simple ‘Golden Rules’ of depth of field.

  • Low ‘f’ numbers have shallow depth of field
  • High ‘f’ numbers have greater depth of field
  • With a short lens you can get lots of depth of field
  • With a long lens you get only a little depth of field

large depth of fieldBy combining these ‘rules’ you can get the depth of field you want.

For example - ­ a long lens (250mm) combined with a low ‘f’ number (f5.6) will give you a shallow depth of field - like in the shot of the tripod head.

You could do this with a portrait, a flower, a crack in the brickwork - ­ anything you like. The effect will always be the same.

A short lens combined with a high ‘f’ number will give you maximum front to back sharpness. Great for landscapes or even close up details like this place setting at a wedding.

OK I know I said no pretty pics this time - ­ but I didn’t want you to get bored!

In my next photography tips I’ll explain more about focal lengths and how you can add mood and alter perspective with them. Long lenses do more than just bring far off things closer you know. For more about this, watch the Using Long Camera Lenses video in our Photography Videos.

Meanwhile ­ if you’d like some help taking your photography to the next level, our beginners photography course download will get you going in the shortest possible time.

Our wedding photography course download will teach you everything you need to know about photographing weddings.

And our One-to-One photography courses are tailor made for each individual so you get maximum benefit from spending time with me.

mike browneHappy shooting ­ see you next time….